The parallelization of optical communications using wavelength division multiplexing (WDM) has led to tremendous increases in fiber-optic channel capacity over the past decade. The use of numerous WDM channels to transmit information leverages the vast available spectrum of the optical channel (such as a guided, e.g., fiber-optic, or unguided, e.g., free space, optical channel) which exceeds many THz, with each channel preferably using a manageable amount of bandwidth (e.g., GHz-class) that may, in practice, be generated with available electronics.
Many applications of this technology require implementations that have small size, low weight, and low power consumption (SWAP). For example, space-based communications, especially those over the distances that exceed a typical Earth orbit, are usually power-starved, so simple low-SWAP receiver (RX) implementations with good sensitivity are desirable; improvements in RX sensitivity provide more link margin, extend link distances, and enable lower-power transmitters (TXs), an effect that lowers nonlinear impairments and may provide benefit in both fiber-optic guided and free-space applications. The need exists for a wide-band parallel optical communication receiver, with good receiver sensitivity, reduced electrical bandwidth, simplified implementation, and lower size, weight, and power (SWAP).